Thirty adults and children gathered for a Sunday afternoon walk looking for signs of fall in the Hillwood Manor section of Sligo on October 22, 2006, in an outing led by naturalist Frank Boyle (at right, in olive baseball cap).
In no time, we spotted an abandoned bird’s nest about 20 feet up in a hickory tree. Frank speculated that it could be a robin’s. The average height of a robin’s nest in DC and Maryland is 13 feet, though it ranges considerably from 1 to 60 ft.
Further along the paved path, Frank showed us a a patch of white stain on porcelain berry, which he said was “owl whitewash.” Since owls and other predator birds eject much of their undigested SOLID material as regurgitated pellets, their droppings are almost entirely liquid. Frank thought this was from a screech or barred owl, since owls drop their wash straight down from a high perch, while hawks (and falcons) project their wash in a stream that can be 10 feet long.
Not far away, Frank found this gall on a red oak sapling. Galls are homes for developing insect larvae, and occur on many Sligo trees, including oaks, willows, maples, birches, beeches, hickories, pines, elms, and Witch-hazel (as well as herbaceceous species, especially goldenrod). In oaks, a gall is formed when a single wasp larva in the tree exudes a chemical that stimulates runaway woody growth around it. After two-years of development, it finally emerges — that is, if the gall hasn’t been parasitized by another insect or pecked into by a woodpecker, blue jay, or chickadee in search of a meal.
A bonus discovery under one log were tiny white spheres that Frank thought might be centipede eggs.